Pry-off latch for disconnect switch



y 6, 1965 s. B. SPRAGUE 3,193,632

FRY-OFF LATCH FOR DISCONNECT SWITCH Filed June 20, 1961 IN VEN TOR.

STfPHE N B. SPRAGl/E @143 24/23/33 ATTORNEY United States Patent Thisinvention relates to electric switches and more particularly todisconnect switches adapted to be operated by a hook stick.

Disconnect switches are usually mounted on elevated structures forsafety reasons. They are operated, from the ground, by an insulatedoperator or hook stick which cooperates with portions of the switch inthe opening and closing operations. Disconnect switches must be capableof safely carrying high currents and also overloads due to momentaryfaults. In order to assure continuity of the circuit and to guardagainst non-intentional opening of the switch latching means is providedto maintain the switch in the closed circuit position.

Disconnect switches must be capable of being operated under adverseweather conditions. Ice formation has been an acute problem. The switchmust be capable of being opened even though encumbered by the heavy icecoating. Heretofore, disconnect switches have had separate latches andpry-off means for breaking the ice coating requiring separateoperations. The latch means and operating means heretofore employed havehad a large number of parts which, due to the ice coating, made openingof the switch difiicult. It is an object of this invention to improvethe reliability of disconnect switches under severe weather conditions.

It is yet another object of the invention to provide a novel disconnectswitch capable of being opened with a single continuous motion.

It is another object of this invention to provide an improved hookoperated disconnect switch with increased ease of opening under icingconditions.

These and other objects and advantages are achieved in an illustrativeembodiment of the invention described in detail below. In theillustrative embodiment of the invention, a hook-operated disconnectswitch is provided having a movable switch blade and a companioncontact. A combined latch and pry-off member is mounted on the switchblade for engagement with a portion of the companion contact structure.The mounting means for the combined member provides for the pivotalmovement of the member in the plane of the switch blade and for themovement of the member along the longitudinal axis of the blade withinsaid plane. Biasing means mounted on the blade urges the member in thelatch retaining direction when the switch is closed.

For a better understanding of the invention, reference is made to thefollowing description taken in conjunction with the accompanyingdrawings depicting an illustrative embodiment of the invention in which:

FIG. 1 is a perspective view of a disconnect switch embodying variousaspects of the invention;

FIG. 2 is a fragmentary sectional view of a portion of the latchstructure as viewed from the horizontal plane designated 22 in FIG. 1,drawn to larger scale;

Referring to the drawings, the disconnect switch It) "ice comprises abase channel 11 upon which are mounted a pair of insulator stacks 12,14. The switch It is shown in FIG. 1 with the channel 11 mountedvertical. The switch blade 16 is pivoted to swing in the vertical planeabout pin 18 carried by bracket 20 secured to the top of the insulatorstack 14. Bracket 20 has bolt holes 22 for attaching the clamp of atransmission line conductor.

Highly conductive contact inserts 24 are secured to the legs 26, 28 ofthe switch blade 16. Legs 26, 28 are spaced apart at one end by thebracket 20 and connected together intermediate their ends by a spacerpin 30.

Contact bracket 32 is carried by insulator stack 12. Contacts 34 areformed on one end of the member 32 in the form of a pair of resilientseparated fingers. Blade contacts 24 engage companion contacts 34 in theclosed position of the switch. Bracket 32 is provided with bolt holes 36for a cable clamp, to connect the other transmission line conductor tothe swtich.

A combined latch and pry-cit member 40 is provided with an opening 42for engagement by the hook stick 43 shown in phantom in FIGS. 4, 5 and6. The combined pry-off member and latch 40 is mounted on the switchblade 16 by a pin 44 through the switch blade legs 26, 28. The inturnedends 45 of the legs 26, 28 center the member 40 with respect to thelongitudinal axis of the blade 16. Latch 40 has a slot 46 which allowsthe latch to be moved along the switch blade 16 relative to pin 44 aswell as allowing the latch to pivot about pin 44 in the plane of theaxis of the blade. Slot 46 may be described as having a forward end 46aand rearward end 4612.

Referring to FIG. 2, catch 50 is mounted by bolt 52 on the companioncontact bracket 32 adjacent the upstanding separated contact legs 34.The catch may be generally described as having the form of a truncatedcone 54 on a cylindrical base 56 of smaller diameter. The cone has a topsurface 58, inclined sides 60, lower peripheral edge 62 andan overhang64 between the edge 62 and the base 56.

Latch 40 has an arm 66 adapted to engage the overhang 64 of the catch 50when the switch is closed. The combined member 40 is resiliently urgedinto engagement with the catch 50 by tension spring 68. One end ofspring 68 engages spacer pin 36 and the other end of the spring engagesaperture 70 in leg 72 of member 40. Latch 40 does not form a significantpart of the current path in the switch. Stop pin 74 is carried by thelatch 49 and is engageable with the edge of switch blade 16 remote frombracket 32 when the switch is either being closed or opened as will bedescribed in greater detail below.

The mode of operation of the illustrative embodiment will be morereadily understood if the description is begun with the switch 10 in theclosed position shown in FIG, 1. In the closed position the catch 50 isengaged by the combined member 40 and the resilient cont-act fingers 34press against the contacts 24 carried by the switch .blade 16. Latchmember 40 is held against the catch 50 by the spring means 68. Spring 68has moved the latch downwardly, in FIG. 3, until the end 46a of the slotalmost contact-s pin 44. Leg 66 of the latch 40 is hooked under theoverhang 64 of the stop 50. In this position, catch 56 is firmly engagedby the latch member 40 since spring 68 acts along a line which passesthrough the center of the pivot pin 44. There is no component of thelatching force present which would tend to drive the latch member 4% tothe open position.

When it is desired to open the switch 10 a hook stick 43 is engaged inthe opening 42 in the latch member 40. When the hook stick is pulleddownwardly, as viewed in FIG. 1, the initial reaction of the latch 40 isto pivot clockwise about the pin 44 as viewed in FIG, 3 to the positionshown in phantom FIG. 4. The initial movement of the latch about thepivot pin 44 causes the leg 66 to disengage the overhang 64 of thecatchSt). Continued movement of the latch 49 by the hook stick'43 bringsleg 72 into contact with the top surface 58 of the catch 50. This isillustrated in phantom in FIG. 4. Continued application of openingthrust by the hook stick forces the'leg 7-2 to push against the catchtop 58 prying the blade 16 away from the closed position and causingseparation of the contacts. The movement of the latch '46 which drivesthe leg '72. against the catch 53 may be described as a'pry-offoperation. The leverage arrangement of the respective'lcverarms formedby the portions latch member 40 on opposite side of the pivot pin 44 issuch that an effective multiplication of the separating effort isachieved. This prying effort has been found sufficient to break icecoatings formed .on the switch blade and contacts. Continued pivotalmovement of the latch 49 about the pin 44 brings the stop 74 intocontact with the upper'surfaceof the blade 16 as viewed in FIG. 5 'atwhich time continued pivotal movement of the latch 49 is arrested by thecoaction of the pin. 74.

ing movement relative thereto, said latch member having a'lat-ch portionand a pry-off portion, catch means mounted on said contact means andhaving latch engaging means for engagement by said latch portion whensaid switch is closed and said lat-ch member moved in an engagingdirection, the pry-off portion o-fsaid latch member engaging said catchmeans when said latch member is moved in a disengaging direction'toforce said switchblade means out of engagement with said contact means.

2 A hook-operated disconnect switch comprising astationary contact annda switchblade mounted in spaced relation from said stationary contactfor movement into and out of resilient engagement therewith, saidengagement establishing frictional forces in said members normallyresisting the separation thereof, a unitary pry-off latch member mountedon said Switchblade for limited pivotal and sliding movement in theplane thereof, said latch member having a latch portion and a pry-offportion, a catch member having latch engaging means mounted on saidstationary contact for engagement by said latch portion when saidswitchis closed and said latch 7 member is rotated in an engaging direction,biasing means last described, to the closed position shown in thedrawings'by the use of the hook stick 43. When the switch is at rest inthe open position the spring 68 causes the combined member 40 to pivot'on pin 44 on the blade until the pin 74 bears against the blade 16. Whenthe hook stick 43 is used to drive the switch closed the stop 74 locksthe lat-ch 40 against pivotal movement relative to the blade during theclosing operation andthe latch 40 and blade 16 then move as a position.As the switch bladepivot-s about pin '18, the contact-s 34, 24 engage.Also, the end of the arm 66 of the latch 40 engages the inclined side 60of the catch .50 at the start of the latching operation. Theapplicationof the closing force through the hook stick 43 to the latch 40 causesthe latch 40 to slide forward along the longitudinal axis of the catch50. Stop pin 74 slides unit toward the closed forurginglsaid latchportion in the catch engaging direction, said lat-ch member engagingsaidcatch in the closed position of said switch and being held :thereagainstby said biasing means, said pry-off portion of said 'latch memberengaging said catch member when said latch member is pivoted in thedisengaging direction to force said switchblade to move against saidfrictional forces and out of engagement withsaid stationary contact.

3. Aihook-operated disconnect switch com-prising a stationary cont-actand 'a switchblade mounted in' spaced relation from said stationarycontact for movement into and out of resilient engagement with saidstationary contact, said engagement establishing frictional forces insaid members normally resisting the separation thereof, a unitarypry-off latch member mounted for limited movement on said switchbladeand. having a hook-engaegable portion, said latch member having a latchportion and a pry-off portion, a catch member mounted on said stationarycontact for overlapping engagement bysaid latch along the surface of theblade 16 and prevents the latch 1 member 49 from pivoting as arm'66slides along the side 60 of the catch 54) (see FIG. 6). When the end ofthe arm 66 snaps over the edge 62 of the catch 50 the leg engages theoverhang 64 and the latch snapsback along the longitudinal axis of theblade 16 to the latched position under the force of spring 68 (FIG. 3).

The combined lat-ch member 40 thus incorporates a latching function aswell as aunitary pry-off mechanism. The described apparatus permits theopening or closing operation to be performed .by a single, continu ouspush or pull, on the member 40. The pin-and-slot lost motion connectionbetween the combined member 40 and' blade 16 allows the latch 40 toengage the catch 50 with a minimum numberlof moving parts, and stop pin74 cooperates with the edge of switch blade 16 to provide for limitedswing of latch member'4tl relative to the switch blade and to form adrive connection to the blade at both 'arcuate'limits of the swing foropening and closing the ing frictional forces in said members normallyresisting the separation thereof, a unitary. pry-off latchmember mountedon said switchblade means for pivotal and'slidsaid stationary contactmeans, said engagement establish portion when said switch is closed,said mounting means also providing for relative sliding movement betweensaid latch member and said switchblade in the direction of saidoverlapping engagement, resilient means urging said latch portion in anoverlapping direction,.said pry-off port-ion cooperatively engaging saidcatch member when said latch member is pivoted in the disengagingdirection to force said switchblade out of engagement with saidstationary contact.

. 4. A hook-operated disconnect switch comprising a stationary contact:and'a switchblade mounted in spaced relation from said stationarycontact for movement into and out-of resilient engagementwith saidstationary contact, said engagement establishing frictional forces insaid members normally resisting the separation thereof, a unitarypry-off latch member having a hook-engageable portion and being'mountedon said switchblade for pivotal and sliding movement relative thereto,said latch member having a latch portion on one side of said pivotalaxis and a pry-off portion on theother side thereof, a catchmember'mounted on said stationary contact for engagement by said latchportion when said switch is closed, a stop on said latch member forlimiting the movement there-of relative to said switchblade in thecatch- ,engaging direction, spring means'for urging said latch'portionin the catch engaging direction, said latch member engaging said catchin the closed position of said switch 7 itionary contact means andswitchblade means movable into and out of resilient engagement with saidcontact means, said engagement establishing frictional forces in saidmembers normally resisting the separation thereof, a unitary pry-01flatch member pivotally mounted on said Switchblade for forcing saidswitchblade out of engagement with said stationary contact means, saidlatch member having a latch portion on one side of said pivotal axis anda pry-oft portion on the other side thereof, a catch member having theshape of a truncated cone mounted on said stationary contact means forengagement by said latch portion when said switch is closed, a stop onsaid latch member for limiting the movement thereof relative to saidswitchblade in the catch-engaging direction, resilient means for urgingsaid latch portion in the catch engaging direction, said latch memberengaging said catch in the closed position of said switch and being heldthereagainst by said resilient means, the pryofi portion of said latchmember engaging the flattened top of said catch member when said latchmember is pivoted in the disengaging direction to force said switchbladeout of engagement with said stationary contact.

6. A hook-operated dis-connect switch comprising a pair of spacedinsulators, a stationary contact mounted on one insulator, a switchblademounted on the other insulator for pivotal movement into and out ofresilient engagement with said stationary contact, said engagementestablishing frictional forces in said members normally resisting theseparation thereof, a unitary pry-off latch member having ahook-engageable portion, means for pivotally mounting said latch memberon said switchblade adjacent the free end thereof, said mounting meansalso providing for relative sliding movement between said latch memberand said switch-blade, said latch member having a latch portion on oneside of said pivotal axis and a pry-ott portion on the other sidethereof, a catch member having the shape of a truncated cone mounted onsaid stationary contact for engagement by said latch portion when saidswitch is closed, a stop on said latch member for limiting the movementthereof relative to said switchblade in the catch-engaging direction, aspring engaging said latch member and said switchblade for urging saidlatch portion in the catch engaging direction, said latch memberengaging said catch in the closed position of said switch and being heldthereagainst by said spring, said pry-01f portion engaging the flattenedtop of said catch member when said latch member is pivoted in'thedisengaging direction to force said switchblade out of engagement withsaid stationary contact.

References Cited by the Examiner UNITED STATES PATENTS 1,535,778 4/25Johnson et a1. 200-169 2,566,917 9/51 Armstrong 20048 X BERNARD A,GILHEANY, Primary Examiner. ROBERT K. SOHAEFER, Examiner.

1. A HOOK-OPERATED DISCONNECTED SWITCH COMPRISING STATIONARY CONTACTMEANS AND SWITCHABLE MEANS MOUNTED FOR MOVEMENT INTO AND OUT OFRESILIENT ENGAGEMENT WITH SAID STATIONARY CONTACT MEANS, SAID ENGAGEMENTESTABLISHING FRICTIONAL FORCES IN SAID MEMBERS NORMALLY RESISTING THESEPARATION THEREOF, A UNITARY PRY-OFF LATCH MEMBER MOUNTED ON SAIDSWITCHABLE MEANS FOR PIVOTAL AND SLIDING MOVEMENT RELATIVE THERETO, SAIDLATCH MEMBER HAVING A LATCH PORTION AND A PRY-OFF PORTION, CATCH MEANSMOUNTED ON SAID CONTACT MEANS AND HAVING LATCH ENGAGING MEANS FORENGAGEMENT BY SAID LATCH PORTION WHEN SAID SWITCH IS CLOSED AND SAIDLATCH MEMBER MOVED IN AN ENGAGING DIRECTION, THE PRY-OFF PORTION OF SAIDLATCH MEMBER ENGAGING SAID CATCH MEANS WHEN SAID LATCH MEMBER IS MOVEDIN A DISENGAGING DIRECTION TO FORCE SAID SWITCHBLADE MEANS OUT OFENGAGEMENT WITH SAID CONTACT MEANS.